Re: [PATCH v2] Events when inferior is modified

[Nick Bull <nicholaspbull at gmail dot com>]

On 25 November 2013 09:48, Phil Muldoon <pmuldoon@redhat.com> wrote:
> On 18/11/13 12:39, Nick Bull wrote:
>
>> This patch adds new observers, and corresponding Python events, for
>> various actions on an inferior: calling a function (by hand),
>> modifying registers or modifying memory.
>
> Thanks just a few nits and some questions. I did not see tests for
> these, and also, documentation?  In any case, both are needed.

Now with the nits addressed, rejigging to use the existing
memory_changed observer, some test coverage and documentation.
make check ran without regressions.

Nick

gdb/ChangeLog

2013-12-09  Nick Bull  <nicholaspbull@gmail.com>

        * Makefile.in: add py-infcallevent.c / py-infcallevent.o.
        * doc/observer.texi (inferior_call_pre, inferior_call_post
        register_changed): New observers.
        * infcall.c (call_function_by_hand): Notify observer before and
        after inferior call.
        * python/py-event.h (inferior_call_kind): New enum.
        (emit_inferior_call_event): New prototype.
        (emit_register_changed_event): New prototype.
        (emit_memory_changed_event): New prototype.
        * python/py-events.h (events_object): New registries
	inferior_call, memory_changed and register_changed.
        * python/py-evts.c (gdbpy_initialize_py_events): Add the
        inferior_call, memory_changed and register_changed registries.
        * python/py-infcallevent.c: New.
        * python/py-inferior.c (python_on_inferior_call_pre)
        (python_on_inferior_call_post, python_on_register_change)
        (python_on_memory_change): New functions.
        (gdbpy_initialize_inferior): Attach python handler to new
        observers.
        * python/python-internal.h:
        (gdbpy_initialize_inferior_call_pre_event)
        (gdbpy_initialize_inferior_call_post_event)
        (gdbpy_initialize_register_changed_event)
        (gdbpy_initialize_memory_changed_event): New prototypes.
        * python/python.c (_initialize_python): Initialize new events.
	* valops.c (value_assign): Notify register_changed observer.

gdb/testsuite/ChangeLog

2013-12-09  Nick Bull  <nicholaspbull@gmail.com>

	* gdb.python/py-events.py (inferior_fn_handler): New.
	(register_changed_handler, memory_changed_handler): New.
	(test_events.invoke): Register new handlers.
	* gdb.python/py-events.exp: Add tests for inferior call,
	memory_changed and register_changed events.


diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index be30dfd..40e9875 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -296,6 +296,7 @@ SUBDIR_PYTHON_OBS = \
 	py-framefilter.o \
 	py-function.o \
 	py-gdb-readline.o \
+	py-infcallevent.o \
 	py-inferior.o \
 	py-infthread.o \
 	py-lazy-string.o \
@@ -332,6 +333,7 @@ SUBDIR_PYTHON_SRCS = \
 	python/py-framefilter.c \
 	python/py-function.c \
 	python/py-gdb-readline.c \
+	python/py-infcallevent.c \
 	python/py-inferior.c \
 	python/py-infthread.c \
 	python/py-lazy-string.c \
@@ -2217,6 +2219,10 @@ py-gdb-readline.o: $(srcdir)/python/py-gdb-readline.c
 	$(COMPILE) $(PYTHON_CFLAGS) $(srcdir)/python/py-gdb-readline.c
 	$(POSTCOMPILE)

+py-infcallevent.o: $(srcdir)/python/py-infcallevent.c
+	$(COMPILE) $(PYTHON_CFLAGS) $(srcdir)/python/py-infcallevent.c
+	$(POSTCOMPILE)
+
 py-inferior.o: $(srcdir)/python/py-inferior.c
 	$(COMPILE) $(PYTHON_CFLAGS) $(srcdir)/python/py-inferior.c
 	$(POSTCOMPILE)
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 87d5145..f4adef1 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -25808,6 +25808,30 @@ A reference to the object file 
(@code{gdb.Objfile}) which has been loaded.
 @xref{Objfiles In Python}, for details of the @code{gdb.Objfile} object.
 @end defvar

+@item inferior_call_pre
+Emits @code{gdb.InferiorCallPreEvent} which indicates that a function in
+the inferior is about to be called.
+
+@item inferior_call_post
+Emits @code{gdb.InferiorCallPostEvent} which indicates that a function in
+the inferior has returned.
+
+@item memory_changed
+Emits @code{gdb.MemoryChangedEvent} which indicates that the memory of the
+inferior has been modified by the GDB user, for instance via a command like
+@code{set *addr = value}.  The event has the following attributes:
+
+@defvar MemoryChangedEvent.address
+The start address of the changed region.
+@end defvar
+@defvar MemoryChangedEvent.length
+Length in bytes of the changed region.
+@end defvar
+
+@item register_changed
+Emits @code{gdb.RegisterChangedEvent} which indicates that a register 
in the
+inferior has been modified by the GDB user.
+
 @end table

 @node Threads In Python
diff --git a/gdb/doc/observer.texi b/gdb/doc/observer.texi
index f753965..c20fec5 100644
--- a/gdb/doc/observer.texi
+++ b/gdb/doc/observer.texi
@@ -253,6 +253,18 @@ The trace state variable @var{tsv} is deleted.  If 
@var{tsv} is
 The trace state value @var{tsv} is modified.
 @end deftypefun

+@deftypefun void inferior_call_pre (void)
+An inferior function is about to be called.
+@end deftypefun
+
+@deftypefun void inferior_call_post (void)
+An inferior function has just been called.
+@end deftypefun
+
+@deftypefun void register_changed (void)
+One or more registers in the inferior have been modified.
+@end deftypefun
+
 @deftypefun void test_notification (int @var{somearg})
 This observer is used for internal testing.  Do not use.
 See testsuite/gdb.gdb/observer.exp.
diff --git a/gdb/infcall.c b/gdb/infcall.c
index 212997f..7c1a5ae 100644
--- a/gdb/infcall.c
+++ b/gdb/infcall.c
@@ -36,6 +36,7 @@
 #include "ada-lang.h"
 #include "gdbthread.h"
 #include "exceptions.h"
+#include "observer.h"

 /* If we can't find a function's name from its address,
    we print this instead.  */
@@ -611,6 +612,8 @@ call_function_by_hand (struct value *function, int 
nargs, struct value **args)
       target_values_type = values_type;
     }

+  observer_notify_inferior_call_pre ();
+
   /* Determine the location of the breakpoint (and possibly other
      stuff) that the called function will return to.  The SPARC, for a
      function returning a structure or union, needs to make space for
@@ -844,6 +847,8 @@ call_function_by_hand (struct value *function, int 
nargs, struct value **args)
     e = run_inferior_call (tp, real_pc);
   }

+  observer_notify_inferior_call_post ();
+
   /* Rethrow an error if we got one trying to run the inferior.  */

   if (e.reason < 0)
diff --git a/gdb/python/py-event.h b/gdb/python/py-event.h
index f0ff629..c17079d 100644
--- a/gdb/python/py-event.h
+++ b/gdb/python/py-event.h
@@ -105,6 +105,15 @@ typedef struct
 extern int emit_continue_event (ptid_t ptid);
 extern int emit_exited_event (const LONGEST *exit_code, struct 
inferior *inf);

+typedef enum
+{
+  inferior_call_pre,
+  inferior_call_post,
+} inferior_call_kind;
+
+extern int emit_inferior_call_event (inferior_call_kind kind);
+extern int emit_register_changed_event (void);
+extern int emit_memory_changed_event (CORE_ADDR addr, ssize_t len);
 extern int evpy_emit_event (PyObject *event,
                             eventregistry_object *registry)
   CPYCHECKER_STEALS_REFERENCE_TO_ARG (1);
diff --git a/gdb/python/py-events.h b/gdb/python/py-events.h
index 4ec3832..d158211 100644
--- a/gdb/python/py-events.h
+++ b/gdb/python/py-events.h
@@ -46,6 +46,9 @@ typedef struct
   eventregistry_object *cont;
   eventregistry_object *exited;
   eventregistry_object *new_objfile;
+  eventregistry_object *inferior_call;
+  eventregistry_object *memory_changed;
+  eventregistry_object *register_changed;

   PyObject *module;

diff --git a/gdb/python/py-evts.c b/gdb/python/py-evts.c
index 1ff3022..76f923b 100644
--- a/gdb/python/py-evts.c
+++ b/gdb/python/py-evts.c
@@ -73,6 +73,18 @@ gdbpy_initialize_py_events (void)
   if (add_new_registry (&gdb_py_events.exited, "exited") < 0)
     return -1;

+  if (add_new_registry (&gdb_py_events.inferior_call,
+			"inferior_call") < 0)
+    return -1;
+
+  if (add_new_registry (&gdb_py_events.memory_changed,
+			"memory_changed") < 0)
+    return -1;
+
+  if (add_new_registry (&gdb_py_events.register_changed,
+			"register_changed") < 0)
+    return -1;
+
   if (add_new_registry (&gdb_py_events.new_objfile, "new_objfile") < 0)
     return -1;

diff --git a/gdb/python/py-infcallevent.c b/gdb/python/py-infcallevent.c
new file mode 100644
index 0000000..4c8505d
--- /dev/null
+++ b/gdb/python/py-infcallevent.c
@@ -0,0 +1,172 @@
+/* Python interface to inferior function events.
+
+   Copyright (C) 2013 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see 
<http://www.gnu.org/licenses/>.  */
+
+#include "defs.h"
+#include "py-event.h"
+
+static PyTypeObject inferior_call_pre_event_object_type;
+static PyTypeObject inferior_call_post_event_object_type;
+static PyTypeObject register_changed_event_object_type;
+static PyTypeObject memory_changed_event_object_type;
+
+static PyObject *
+create_inferior_call_event_object (int flag)
+{
+  PyObject * event;
+
+  switch (flag)
+    {
+    case inferior_call_pre:
+      event = create_event_object (&inferior_call_pre_event_object_type);
+      break;
+    case inferior_call_post:
+      event = create_event_object (&inferior_call_post_event_object_type);
+      break;
+    default:
+      return NULL;
+    }
+
+  return event;
+}
+
+static PyObject *
+create_register_changed_event_object (void)
+{
+  PyObject * event;
+
+  event = create_event_object (&register_changed_event_object_type);
+
+  return event;
+}
+
+static PyObject *
+create_memory_changed_event_object (CORE_ADDR addr, ssize_t len)
+{
+  PyObject * event;
+  PyObject *addr_obj = NULL;
+  PyObject *len_obj = NULL;
+  int failed;
+
+  event = create_event_object (&memory_changed_event_object_type);
+
+  if (!event)
+    goto fail;
+
+  addr_obj = PyLong_FromLongLong (addr);
+  if (addr_obj == NULL)
+    goto fail;
+
+  failed = evpy_add_attribute (event, "address", addr_obj) < 0;
+  Py_DECREF (addr_obj);
+  if (failed)
+    goto fail;
+
+  len_obj = PyLong_FromLong (len);
+  if (len_obj == NULL)
+    goto fail;
+
+  failed = evpy_add_attribute (event, "length", len_obj) < 0;
+  Py_DECREF (len_obj);
+  if (failed)
+    goto fail;
+
+  return event;
+
+ fail:
+  Py_XDECREF (addr_obj);
+  Py_XDECREF (event);
+
+  return NULL;
+}
+
+/* Callback function which notifies observers when an event occurs which
+   calls a function in the inferior.
+   This function will create a new Python inferior-call event object.
+   Return -1 if emit fails.  */
+
+int
+emit_inferior_call_event (inferior_call_kind flag)
+{
+  PyObject *event;
+
+  if (evregpy_no_listeners_p (gdb_py_events.inferior_call))
+    return 0;
+
+  event = create_inferior_call_event_object (flag);
+  if (event != NULL)
+    return evpy_emit_event (event, gdb_py_events.inferior_call);
+  return -1;
+}
+
+int
+emit_memory_changed_event (CORE_ADDR addr, ssize_t len)
+{
+  PyObject *event;
+
+  if (evregpy_no_listeners_p (gdb_py_events.memory_changed))
+    return 0;
+
+  event = create_memory_changed_event_object (addr, len);
+  if (event != NULL)
+    return evpy_emit_event (event, gdb_py_events.memory_changed);
+  return -1;
+}
+
+int
+emit_register_changed_event (void)
+{
+  PyObject *event;
+
+  if (evregpy_no_listeners_p (gdb_py_events.register_changed))
+    return 0;
+
+  event = create_register_changed_event_object ();
+  if (event != NULL)
+    return evpy_emit_event (event, gdb_py_events.register_changed);
+  return -1;
+}
+
+
+GDBPY_NEW_EVENT_TYPE (inferior_call_pre,
+		      "gdb.InferiorCallPreEvent",
+		      "InferiorCallPreEvent",
+		      "GDB inferior function pre-call event object",
+		      event_object_type,
+		      static);
+
+GDBPY_NEW_EVENT_TYPE (inferior_call_post,
+		      "gdb.InferiorCallPostEvent",
+		      "InferiorCallPostEvent",
+		      "GDB inferior function post-call event object",
+		      event_object_type,
+		      static);
+
+GDBPY_NEW_EVENT_TYPE (register_changed,
+		      "gdb.RegisterChangedEvent",
+		      "RegisterChangedEvent",
+		      "GDB register change event object",
+		      event_object_type,
+		      static);
+
+GDBPY_NEW_EVENT_TYPE (memory_changed,
+		      "gdb.MemoryChangedEvent",
+		      "MemoryChangedEvent",
+		      "GDB memory change event object",
+		      event_object_type,
+		      static);
diff --git a/gdb/python/py-inferior.c b/gdb/python/py-inferior.c
index 1a1b774..28f6f7d 100644
--- a/gdb/python/py-inferior.c
+++ b/gdb/python/py-inferior.c
@@ -118,6 +118,58 @@ python_on_resume (ptid_t ptid)
 }

 static void
+python_on_inferior_call_pre (void)
+{
+  struct cleanup *cleanup;
+
+  cleanup = ensure_python_env (target_gdbarch (), current_language);
+
+  if (emit_inferior_call_event (inferior_call_pre) < 0)
+    gdbpy_print_stack ();
+
+  do_cleanups (cleanup);
+}
+
+static void
+python_on_inferior_call_post (void)
+{
+  struct cleanup *cleanup;
+
+  cleanup = ensure_python_env (target_gdbarch (), current_language);
+
+  if (emit_inferior_call_event (inferior_call_post) < 0)
+    gdbpy_print_stack ();
+
+  do_cleanups (cleanup);
+}
+
+static void
+python_on_memory_change (struct inferior *inferior, CORE_ADDR addr, 
ssize_t len, const bfd_byte *data)
+{
+  struct cleanup *cleanup;
+
+  cleanup = ensure_python_env (target_gdbarch (), current_language);
+
+  if (emit_memory_changed_event (addr, len) < 0)
+    gdbpy_print_stack ();
+
+  do_cleanups (cleanup);
+}
+
+static void
+python_on_register_change (void)
+{
+  struct cleanup *cleanup;
+
+  cleanup = ensure_python_env (target_gdbarch (), current_language);
+
+  if (emit_register_changed_event () < 0)
+    gdbpy_print_stack ();
+
+  do_cleanups (cleanup);
+}
+
+static void
 python_inferior_exit (struct inferior *inf)
 {
   struct cleanup *cleanup;
@@ -794,6 +846,10 @@ gdbpy_initialize_inferior (void)
   observer_attach_thread_exit (delete_thread_object);
   observer_attach_normal_stop (python_on_normal_stop);
   observer_attach_target_resumed (python_on_resume);
+  observer_attach_inferior_call_pre (python_on_inferior_call_pre);
+  observer_attach_inferior_call_post (python_on_inferior_call_post);
+  observer_attach_memory_changed (python_on_memory_change);
+  observer_attach_register_changed (python_on_register_change);
   observer_attach_inferior_exit (python_inferior_exit);
   observer_attach_new_objfile (python_new_objfile);

diff --git a/gdb/python/python-internal.h b/gdb/python/python-internal.h
index 125670e..8eba303 100644
--- a/gdb/python/python-internal.h
+++ b/gdb/python/python-internal.h
@@ -393,6 +393,14 @@ int gdbpy_initialize_breakpoint_event (void)
   CPYCHECKER_NEGATIVE_RESULT_SETS_EXCEPTION;
 int gdbpy_initialize_continue_event (void)
   CPYCHECKER_NEGATIVE_RESULT_SETS_EXCEPTION;
+int gdbpy_initialize_inferior_call_pre_event (void)
+  CPYCHECKER_NEGATIVE_RESULT_SETS_EXCEPTION;
+int gdbpy_initialize_inferior_call_post_event (void)
+  CPYCHECKER_NEGATIVE_RESULT_SETS_EXCEPTION;
+int gdbpy_initialize_register_changed_event (void)
+  CPYCHECKER_NEGATIVE_RESULT_SETS_EXCEPTION;
+int gdbpy_initialize_memory_changed_event (void)
+  CPYCHECKER_NEGATIVE_RESULT_SETS_EXCEPTION;
 int gdbpy_initialize_exited_event (void)
   CPYCHECKER_NEGATIVE_RESULT_SETS_EXCEPTION;
 int gdbpy_initialize_thread_event (void)
diff --git a/gdb/python/python.c b/gdb/python/python.c
index 1873936..85cbefa 100644
--- a/gdb/python/python.c
+++ b/gdb/python/python.c
@@ -1684,6 +1684,10 @@ message == an error message without a stack will 
be printed."),
       || gdbpy_initialize_signal_event () < 0
       || gdbpy_initialize_breakpoint_event () < 0
       || gdbpy_initialize_continue_event () < 0
+      || gdbpy_initialize_inferior_call_pre_event () < 0
+      || gdbpy_initialize_inferior_call_post_event () < 0
+      || gdbpy_initialize_register_changed_event () < 0
+      || gdbpy_initialize_memory_changed_event () < 0
       || gdbpy_initialize_exited_event () < 0
       || gdbpy_initialize_thread_event () < 0
       || gdbpy_initialize_new_objfile_event ()  < 0
diff --git a/gdb/testsuite/gdb.python/py-events.exp 
b/gdb/testsuite/gdb.python/py-events.exp
index 390a2ba..1027866 100644
--- a/gdb/testsuite/gdb.python/py-events.exp
+++ b/gdb/testsuite/gdb.python/py-events.exp
@@ -79,6 +79,26 @@ all threads stopped"

 delete_breakpoints

+# Test inferior call events
+gdb_test "call do_nothing()" ".*event type: pre-call.*
+.*event type: continue.*
+.*event type: post-call.*"
+
+# Test register changed event
+gdb_test_no_output {set $old_sp = $sp}
+gdb_test {set $sp = 0} ".*event type: register-changed.*"
+gdb_test {set $sp = 1} ".*event type: register-changed.*"
+gdb_test {set $sp = $old_sp} ".*event type: register-changed.*"
+
+# Test memory changed event
+gdb_test_no_output {set $saved = *(int*) $sp}
+gdb_test {set *(int*) $sp = 0} ".*event type: memory-changed.*
+.*address: .*
+.*length: .*"
+gdb_test {set *(int*) $sp = $saved} ".*event type: memory-changed.*
+.*address: .*
+.*length: .*"
+
 #test exited event.
 gdb_test "continue" ".*event type: continue.*
 .*event type: exit.*
diff --git a/gdb/testsuite/gdb.python/py-events.py 
b/gdb/testsuite/gdb.python/py-events.py
index 7601ca1..5586961 100644
--- a/gdb/testsuite/gdb.python/py-events.py
+++ b/gdb/testsuite/gdb.python/py-events.py
@@ -57,6 +57,25 @@ def new_objfile_handler (event):
     print ("event type: new_objfile")
     print ("new objfile name: %s" % (event.new_objfile.filename))

+def inferior_fn_handler (event):
+    if (isinstance (event, gdb.InferiorCallPreEvent)):
+        print ("event type: pre-call")
+    elif (isinstance (event, gdb.InferiorCallPostEvent)):
+        print ("event type: post-call")
+    else:
+        assert False
+
+def register_changed_handler (event):
+    assert (isinstance (event, gdb.RegisterChangedEvent))
+    print ("event type: register-changed")
+
+def memory_changed_handler (event):
+    assert (isinstance (event, gdb.MemoryChangedEvent))
+    print ("event type: memory-changed")
+    print ("address: %s" % (event.address))
+    print ("length: %s" % (event.length))
+
+
 class test_events (gdb.Command):
     """Test events."""

@@ -68,6 +87,9 @@ class test_events (gdb.Command):
         gdb.events.stop.connect (breakpoint_stop_handler)
         gdb.events.exited.connect (exit_handler)
         gdb.events.cont.connect (continue_handler)
+        gdb.events.inferior_call.connect(inferior_fn_handler)
+        gdb.events.memory_changed.connect(memory_changed_handler)
+        gdb.events.register_changed.connect(register_changed_handler)
         print ("Event testers registered.")

 test_events ()
diff --git a/gdb/valops.c b/gdb/valops.c
index d43c758..7c90b4e 100644
--- a/gdb/valops.c
+++ b/gdb/valops.c
@@ -1210,6 +1210,7 @@ value_assign (struct value *toval, struct value 
*fromval)
 	      }
 	  }

+	observer_notify_register_changed ();
 	if (deprecated_register_changed_hook)
 	  deprecated_register_changed_hook (-1);
 	break;